1. Field of the Invention
The present invention relates to a substrate processing apparatus for and a substrate transfer method of transferring a substrate between a cassette which houses a substrate and a substrate processing unit which is adapted to execute a predetermined process on a substrate. Examples of the substrate to be transferred include a semiconductor wafer, a substrate for a liquid crystal display device, a substrate for a plasma display, a substrate for an FED (Field Emission Display), a substrate for an optical disk, a substrate for a magnetic disk, a substrate for a photomagnetic disk, a substrate for a photo-mask and the like.
2. Description of Related Art
A substrate processing apparatus for processing a substrate W such as a semiconductor wafer, a glass substrate for a liquid crystal display panel or the like comprises, for example, a substrate processing module 201 and an indexer module 202 connected thereto, as shown in FIG. 7.
The substrate processing module 201 comprises four processing units 203 placed in a planar arrangement, and a main transfer robot 204 disposed at the center of these processing units 203 as surrounded thereby. The main transfer robot 204 executes a substrate carrying-in/carrying-out operation for carrying an unprocessed substrate W in the processing unit 203 and carrying out a processed substrate W from the processing unit 203.
On the other hand, the indexer module 202 comprises a cassette placing table 206 on which a cassette 205 capable of housing a plurality of substrates W is placed, an indexer robot 207, and a moving mechanism 208 which moves the indexer robot 207 in an arrangement direction of the cassette 205. The indexer robot 207 has access to the cassette 205 placed on the cassette placing table 206 to carry in/out a substrate and also receives/transfers a substrate from/to the main transfer robot 204.
Transfer of a substrate W between the indexer robot 207 and the main transfer robot 204 is conducted in a state that the indexer robot 207 is located in a substrate transfer position P1 where the indexer robot 207 is closest in distance to the main transfer robot 204.
The indexer robot 207 is moved to a position opposed to any of the cassettes 205 placed on the cassette placing table 206 by the moving mechanism 208, and then carries out one unprocessed substrate W from the cassette 205. After the carrying-out, the indexer robot 207 is moved to the substrate transfer position P1 by the moving mechanism 208, and then transfers the unprocessed substrate W to the main transfer robot 204. The main transfer robot 204 carries the unprocessed substrate W thus received from the indexer robot 207 in any of the processing units 203. On the other hand, the main transfer robot 204 takes out a processed substrate W from the processing unit 203 and transfers this processed substrate W to the indexer robot 207 located in the substrate transfer position P1. The indexer robot 207 is moved to a position opposed to any of the cassettes 205 placed on the cassette placing table 206 by the moving mechanism 208 and then houses the processed substrate W thus received from the main transfer robot 204 in the cassette 205.
In such substrate processing apparatus, transfer load on the indexer robot 207 is heavy, whereby the transfer operation thereof has caused lower throughput for the entire apparatus. More specifically, the indexer robot 207 has access to a plurality of cassettes 205 placed on the cassette placing table 206 for carrying-in/carrying-out of a substrate W and also executes a transfer operation of the substrate W to the main transfer robot 204.
The transfer of a substrate W between the indexer robot 207 and the main transfer robot 204 is conducted in the state the indexer robot 207 is position-controlled in the substrate transfer position P1. Therefore, the indexer robot 207 must be moved between the position opposed to a cassette 205 for carrying-in/carrying-out of a substrate W and the substrate transfer position P1.
Accordingly, transfer load on the indexer robot 207 is heavy, whereby the transfer operation thereof has caused lower throughput for the entire apparatus.